The Fortune 50's compliance team carefully evaluated many open source licenses, including MIT, BSD, GPL, Apache, etc. and determined that GPL is the best for their company for internal tools such as these, that must be wholly separate from any product offerings.
And when I say carefully, I mean multiple lawyers, for multiple years, considering many worldwide regulatory compliance laws. GPL won over all the other options.
What about MIT or (two-clause) BSD makes it harder to comply with? Would attribution be an excessive burden for them in case such code ended up in their own products?
My understanding is that BSD and Apache were historically favorable licenses for code that was intended to promote a protocol and make it an industry standard. Easy reuse helped achieving this goal. For example, IIRC FreeBSD's TCP/IP code was repurposed for Windows and MacOS X, and the Apache HTTP server also went a long way toward establishing HTTP as a standard.
Edit: Paragraph on standards.
This necessarily included all updates to the code, subsequent patches by external contributors that come downstream, subsequent patches by internal contributors that go upstream, eventual sunset of the code, etc.
GPL was akin to a bright highlighter stating "internal use only".
